foundation pad not deep enough 9

[Coalhouse]

​

Good Morning.
I am asking for a friend.
a builder who took the freedom to not do as per the structural engineer design.

The foundation pad should have been excavated with 1.25m depth. However, it seems like building control can only see on the photo 0.6m deep and brought this out to the builder attention (and mine)
Building control is saying (me) that according to structural engineer design, it should be 1.25m. however I can get another qualified structural engineer to sign off the 0.6m depth foundation. (note that the excavation has been now filled with concrete).

What are my options? if no structural engineer is willing to sign off the 0.6m depth foundation? I have read a bit and it seems like 1.25m is rather on the high side. is there a quick day to remedy to this. by digging a pile?

I am an engineer myself but from a different tribe (mechanical).
39

 

[Coalhouse]

Wow... why you guys getting so salty! I am an engineer myself. Chartered engineer.So do pls keep to social network social here... I am allowed to pick your brain and it is all I am doing, an informal peer review.

Make no mistake. Your views are just helping me to get a feel and argument to the structural engineer.

I paid for the study (1k£). yes my builder fucked up. they did not consult with the SE. Now it is done. I am trying to understand whether 1.25m is not too much.

and I totally understand the dynamic of CYA (cover your ass). I do it all the time at work...

 

[Ron247]

No one on this site can make a judgement on your situation. We can only provide insight. It will require a qualified person who can directly review your situation, ask questions of all parties involved and then render their best professional conclusion.

But one thing I noted about your "informal peer review", you are advocating for the builder. I personally do engineering for Clients but I cannot become an advocate.

Your views are just helping me to get a feel and argument to the structural engineer.

A non-advocate would be prone to say, "Your views are helping me to get a better feel for this situation."

I think that 1.25m is too much. Why ? because if it not I am totally screwed.

If this is for a builder friend, why are you totally screwed?

Why do you think 1.25m is too much? Several people have given you reasons it may be the correct value. Uplift weight, get down to good soil, etc. Valid reasons. People are getting salty because you are advocating, not engineering. And what is a chartered engineer, I never heard of it. I am in US.

 

[Coalhouse]

Building control is telling me to get a structural engineer to sign it off.
.........
A chartered engineer in the uk is

https://en.wikipedia.org/wiki/Chartered_Engineer_(UK)

 

[Coalhouse]

I want to clarify. I am asking the structural engineer to justify the depth.
And
I paid for a survey and calcs. 1k local money.

 

[Aesur]

@human909 - off topic but I share your observation about the US market and liability, I practice in the US market and feel that we have to consider ourselves more liable because owners and contractors like to look for stuff to do change orders on and or sue you for. In this market if one thing goes wrong, they sue everyone on the project (regardless of discipline) and hope someone settles out of court, which usually happens as insurance companies prefer to settle rather than spend money to fight the case. If they settle they increase your rates, if they fight and you win, they may or may not be able to recoup costs but don't typically increase rates (at least they don't use that as the excuse to raise them). I have actually had a homeowner ask me to design a canopy attached to a trailer that I know will eventually fail in a wind storm so they can do an insurance claim (he claimed his neighbors canopy had recently tore off during a storm and he got a sizeable check from the insurance claim)... I walked away obviously, but I'm willing to bet he found someone who would fall for it.

 

[apsix]

Dig a 600 deep hole to determine the soil at that depth.
If it's fill (made ground) it's not deep enough.
If it's very dense gravel it's all good; show the structural engineer for signoff.

 

[Coalhouse]

ok. I still need to pick your brains. I did not mean to antagonise you. apologies if I did.


The builder says he has dug a hole of 1.25m however he can not prove it. Not taken pictures etc etc. How one could prove this footing thickness? My questions. do you think that if the builder drill a 110mm ( 4 inch) borehole of 1.5m, this would prove the depth of the foundation? (with building control being witness of course)

Using a machine like this one?

 

[Coalhouse]

just found this paper
anyone with experience
Link

 

[phamENG]

What did the engineer of record and/or building control say? They are the ones who have to approve of the method and the results, not us.

 

[dik]

Ok I am done and no doubt most other people here are too.

That was adequate, and leave the discussion... the rest was uncalled for.



Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Coalhouse]

The building control says : "find an a new engineer and a new builder, or find someone who can sign the depth (on the photo)" That is what they are saying.

what I think happened is that the builder did not take photos. Or rather photo was taken by the builder and due to some conflict (between builder and boss) the photo was not sent to the boss. (more likely). Builder want to F*** the boss over but now client is collateral damage.
So now clients needs to prove that foundation is deep enough.

someone mentioned ultrasonic. is this a solution?

I started a new thread because the question is now different. The challenge is to proof that the foundation is deep enough... (surely it is a challenge that you come across often. no?)

 

[Coalhouse]

PhamEng...

https://www.eng-tips.com/viewthread...pprove of the method and the results, not us.

PhamEng...
For the love of GOD... I know who needs to approve the work. your post is no helpful. I am trying to pick your brains. it is a forum. Any of the information provided in that forum has no professional value in the court of law. I know that. it's getting tedious. it is a engineering forum. Focus on the question. i will deal with who needs to approve it.
be helpful. use your experience to help me solve the issue not tell me who needs to approve the solution.

 

[phamENG]

I already have. Dig it up. That's the only way to prove it. I've only seen ultrasonic used on pile foundations. You have to have a geotechnical report with adequate information for the engineer to understand the reflected wave response and estimate a depth. I've never heard of it used on shallow foundations.

 

[le99]

i.25m is not a great length/depth. To verify, you can even hand dig the hole (use the hole digger for utility poles) at the perimeter of the foundation pad and measure using tape. However, you have to think about that if it is sitting at a depth of 0.6m only, then what?

 

[theCorkster]

Boring log - if that is the design engineer's reference, it clearly shows about 1.2 m or so of debris fill. I'm not in the camp that assumes debris fill has any recognized properties when it comes to bearing, settlement or lateral resistance. So the foundation should start at the bottom of the debris in the soil.

 

[Coalhouse]

Has anyone heard of underpinning technique?

 

[Coalhouse]

PhamEng,
pls can you tell me how to treat this ? to replace it would be too costly. so it should be last recourse.
GTE

 

[JoelTXCive]

Little clues would be helpful....Is that a photo of a wall or ceiling.

Also, might want to consider starting a new thread for a new topic & issue.

 

[Coalhouse]

Ceiling. above this is a balcony, which may have leaked for the past 30 years.